Discovery of CD4+ T cell-recognized B. pertussis antigens that reduce airway colonization.

Despite widespread vaccination, Bordetella pertussis (Bp) cases are resurging globally. Although CD4+ T cells are known to be essential for sustained protection, the antigens they recognize are not fully characterized, hindering vaccine refinement. Using immunopeptidomics, bioinformatics, and functional T cell assays, we identified high-affinity epitopes from reference and clinical Bp strains presented on MHC-II I-Ab. A subset of these epitopes stimulated systemic and mucosal CD4+ T cells of mice immunized with heat-killed Bp, and peripheral blood T cells from humans vaccinated with the whole-cell pertussis vaccine. Mice immunized with a subunit vaccine comprising two recombinant proteins identified in our screen were subsequently challenged with Bp. Bacterial burden was nearly eliminated from the lower respiratory tract and significantly reduced in the upper respiratory tract. Th1/Th17-polarized CD4+ tissue-resident memory T cells (Trms) were induced in nasal and pulmonary tissues. Depleting memory CD4+ T cells before challenge abolished protection, confirming that antigen-specific CD4+ T cells are critical for clearing Bp from the respiratory tract. Our integrated antigen identification and T cell assay approach revealed previously untested Bp antigens that elicit protective CD4+ T cell-mediated immunity, suggesting that incorporating them into new vaccines may help curb the resurgence of pertussis.